From nobody Sat Nov 15 17:05:55 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1749666541; cv=none; d=zohomail.com; s=zohoarc; b=YiWt7k+BEU7tm8TRimXH1L8l/mDCHPx0poknfIyivOuyK0HBAwyA84+ivh+b9VDS/TPJ3joVHVR4ydtqHCqUJydM88NvWnhUt7kdlTdUvvH+JQ/8Ru984ZjbT8YW40V1fIXY6/P/c2xe7UDcgpH70UbsNe7w+rzxkarpp7k5jhA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1749666541; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=mt7Eev/XPLmMMdxpFyBJo5Jewpv1gUUY+0ePO6YtQ/c=; b=TcW/BptDXiBbKG2UfH+SfP7ib7M4ScnVCve4x8e4byQtKmXLv9amepork6eOws92/tqtDbK5/vdgCw6oW1nkqKFjDGeG9oTdNt4WO4S/6QCr1/IK69yCvIh4JX+wN+L1ZInZYfRBowIsTAEdR6HPR31jm1Qgz8AEHfJlyIZEgUM= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1749666541560565.1376591433974; Wed, 11 Jun 2025 11:29:01 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uPQAe-0002N8-Uu; Wed, 11 Jun 2025 14:27:33 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uPQ9l-0001WU-GM for qemu-devel@nongnu.org; Wed, 11 Jun 2025 14:26:37 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uPQ9e-0001IL-W0 for qemu-devel@nongnu.org; Wed, 11 Jun 2025 14:26:33 -0400 Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-657-cE_DP5rNMDGSzqy0Vv7YPQ-1; Wed, 11 Jun 2025 14:26:09 -0400 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4ED6918002A4; Wed, 11 Jun 2025 18:26:05 +0000 (UTC) Received: from localhost (unknown [10.2.16.122]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 254A31800284; Wed, 11 Jun 2025 18:26:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1749666374; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=mt7Eev/XPLmMMdxpFyBJo5Jewpv1gUUY+0ePO6YtQ/c=; b=C+2jqb5jcCi16Un6BOubwJl6poL/qN51oQmEfc45UVV3Z3H0XFqQE79au7sgAX7PCWkEtV rzzohiUkCuuPdntJ5w8eOG3c35E7ex0HFE2Sb72dGUHlv8RpfFKVLc0iR3QmsA25FHn21E ZsZUGnA3X9EvfrYxGO0U8Gs30lCUAl4= X-MC-Unique: cE_DP5rNMDGSzqy0Vv7YPQ-1 X-Mimecast-MFC-AGG-ID: cE_DP5rNMDGSzqy0Vv7YPQ_1749666366 From: Stefan Hajnoczi To: qemu-devel@nongnu.org Cc: qemu-ppc@nongnu.org, Daniel Henrique Barboza , qemu-block@nongnu.org, Jesper Devantier , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , Peter Maydell , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Harsh Prateek Bora , Troy Lee , Paolo Bonzini , Hanna Reitz , qemu-s390x@nongnu.org, Halil Pasic , Kevin Wolf , "Michael S. Tsirkin" , qemu-trivial@nongnu.org, Dmitry Fleytman , Jason Wang , Keith Busch , Nicholas Piggin , =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Barrat?= , Fam Zheng , Sven Schnelle , Stefan Hajnoczi , Joel Stanley , Gerd Hoffmann , "Edgar E. Iglesias" , qemu-arm@nongnu.org, Hannes Reinecke , Klaus Jensen , Jeuk Kim , Andrew Jeffery , Alistair Francis , Thomas Huth , Michael Tokarev , Laurent Vivier , Rob Herring , Steven Lee , Jamin Lin , Christian Borntraeger , =?UTF-8?q?C=C3=A9dric=20Le=20Goater?= , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Subject: [PULL 04/31] chardev/char-fd: skip automatic zero-init of large array Date: Wed, 11 Jun 2025 14:25:06 -0400 Message-ID: <20250611182533.200590-5-stefanha@redhat.com> In-Reply-To: <20250611182533.200590-1-stefanha@redhat.com> References: <20250611182533.200590-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1749666543368116600 From: Daniel P. Berrang=C3=A9 The 'fd_chr_read' method has a 4k byte array used for copying data between the socket and device. Skip the automatic zero-init of this array to eliminate the performance overhead in the I/O hot path. The 'buf' array will be fully initialized when reading data off the network socket. Signed-off-by: Daniel P. Berrang=C3=A9 Reviewed-by: Stefan Hajnoczi Message-id: 20250610123709.835102-5-berrange@redhat.com Signed-off-by: Stefan Hajnoczi --- chardev/char-fd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/chardev/char-fd.c b/chardev/char-fd.c index 23bfe3c0b1..6f03adf872 100644 --- a/chardev/char-fd.c +++ b/chardev/char-fd.c @@ -50,7 +50,7 @@ static gboolean fd_chr_read(QIOChannel *chan, GIOConditio= n cond, void *opaque) Chardev *chr =3D CHARDEV(opaque); FDChardev *s =3D FD_CHARDEV(opaque); int len; - uint8_t buf[CHR_READ_BUF_LEN]; + QEMU_UNINITIALIZED uint8_t buf[CHR_READ_BUF_LEN]; ssize_t ret; =20 len =3D sizeof(buf); --=20 2.49.0